Update Hercules CI packages and cachix CLI Nix version

[roberth]

Things done:

• Update Hercules CI packages to latest releases
• Bump nix version used in those and cachix

The files are straightforward cabal2nix-unstable invocations.

• picked unstable because of Add all nix pkg-config modules cabal2nix#662)
• minimal difference with regular cabal2nix
  • different style of license field, presumably better in unstable
  • handling of nix-flake dependency got fixed

I've run hercules-ci-agent with Nix 2.31 for a number of weeks with no issues, exercising the relevant code pathsof cachix push as well.
Nix 2.31 has been the default since September (#440681) so this is still a very conservative update.

cc for review @sandydoo @domenkozar

I will take care to remove these files as haskell-updates makes progress.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

---

Add a 👍 reaction to pull requests you find important.

[roberth]

Thanks!

[wolfgangwalther]

I reverted the first 5 commits in #478767 after the latest hackage bump.

[roberth]

Oh that was quick. Thank you!